Environmentally benign production of graphene oxide

A method of producing isolated graphene oxide sheets directly from a graphitic material, said method comprising:

• a) mixing multiple particles of a graphitic material, and multiple particles of a solid carrier material to form a mixture in an impacting chamber of an energy impacting apparatus;
• b) operating said energy impacting apparatus with a frequency and an intensity for a length of time sufficient for peeling off graphene sheets from said graphitic material and transferring said graphene sheets to surfaces of said solid carrier material particles to produce graphene-coated solid carrier particles inside said impacting chamber;
• and c) sequentially or concurrently oxidizing and separating said graphene sheets from said surfaces of said solid carrier material particles to produce said isolated graphene oxide sheets, wherein said step (c) comprises exposing said graphene sheets to an oxidizing medium, before, during or after the graphene sheets are separated from said solid carrier material particle surfaces, wherein said oxidizing medium is selected from an oxidizing gas or vapor, an oxidizing plasma, or an oxidizing liquid, wherein said oxidizing liquid is selected from a liquid comprising an oxidizer selected from sodium permanganate, transition metal permanganate;
• wherein said step (a) includes adding an oxidizing liquid in said mixture so that said oxidizing liquid acts to partially oxidize said graphene sheets during step (b).